1. Field of the Invention
The present invention relates to a sheet processing apparatus that processes a sheet and an image forming apparatus including the sheet processing apparatus.
2. Description of the Related Art
In the related art, an image forming system in which a common sheet processing apparatus is capable of receiving a sheet from two image forming apparatuses is suggested (see Japanese Patent Laid-Open No. 2004-093984).
The image forming system receives a sheet conveyed from one of the image forming apparatuses through one of inlets of the common sheet processing apparatus and discharges the sheet to a processing tray to be stacked. Further, the image forming system receives a sheet conveyed from the other image forming apparatus through the other inlet of the common sheet processing apparatus and discharges the sheet to the processing tray to be stacked.
Therefore, since a sheet from both image forming apparatuses can be received by the common sheet processing apparatus, one sheet processing apparatus is only required for two image forming apparatuses. Thus, the cost is reduced and the space is saved.
However, in the above-mentioned related art, while the sheet conveyed from one of the image forming apparatuses is discharged and stacked onto the processing tray, the discharging and stacking of the sheet conveyed from the other image forming apparatus to the processing tray need to wait until the sheet processing is completed. Therefore, even though a user has two image forming apparatuses, the sheet processing has a productivity corresponding to one image processing apparatus. Thus, the productivity for entire system is significantly lowered.
As a method for solving the above-mentioned problem, a method for discharging and stacking sheets conveyed from two image forming apparatuses onto a processing tray of a common sheet processing apparatus is suggested. However, if timings to discharge a sheet to the processing tray as illustrated in FIGS. 9A and 18A overlap, leading edges of opposing two sheets which are conveyed from the two image forming apparatuses collide with each other and is jammed.